Mg(OH)_2共沉淀同位素稀释电感耦合等离子体质谱法测定酱油中的微量铅

Determing Pb in Soy Sauces with ID-ICP-MS Coupled with Mg(OH)_2 Co-precipitation

目的：建立Mg（OH）2共沉淀和同位素稀释电感耦合等离子体质谱（ID-ICP-MS）法测定酱油样品中的微量铅。方法：考察并优化pH值和Mg（NO3）2添加量对Pb共沉淀的影响。结果：结果表明,采用Mg（OH）2共沉淀法可有效去除酱油中大量的可溶性盐。用ID-ICP-MS测定酱油中微量Pb的平均加标回收率为93.0%,RSD≤0.4%。结论：利用建立的方法测定13种市售酱油中的微量铅,铅含量在0.01~0.21mg/L之间,均未超过相关的国家标准（GB2717-2003）限量（≤1.0mg/L）。

A method of determining trace Pb in soy sauces was established with isotope dilution inductively coupled plasma mass spectrometry（ID-ICP-MS） coupled with the co-precipitation of Mg（OH）2. The effects of pH values and the amounts of Mg（OH）2 on Pb recovery in the co-precipitation system were discussed and optimized. The results showed that a mean recovery of 93.0% by adding standard of Pb could be achieved with 0.4% of the relative standard deviation （RSD%）. The amounts of trace Pb in soy sauces were measured with the established method. The concentrations of Pb in the samples of thirteen soy sauces ranged from 0.01 to 0.21 mg/L, which was within the limit（≤1.0 mg/L） of the national standard（GB 2717-2003）. The result indicated that the established method was suitable for the measurement of trace lead in soy sauces containing high levels of salt matrixes.